Hello @samir , welcome to our community!
NxSDK as you know is a proprietary software by Intel and is not publicly viewable. If your end goal is to develop SNNs to run on Loihi Chip, then there are two ways. One is of course to use NxSDK to develop one, instructions/tutorials of which can be found on INRC forum. Second method is to use NengoLoihi; it is a python package which is used to run Nengo models on Loihi and uses NxSDK as its backend. You can find more info about NengoLoihi here.
I am linking few examples below as well which shows how to use NengoLoihi for deploying SNNs on Loihi.
https://www.nengo.ai/nengo-loihi/examples/mnist-convnet.html
https://www.nengo.ai/nengo-loihi/examples/cifar10-convnet.html
You can find more examples here.
Apart from this, I myself have a question on how to extend NengoLoihi with new NxSDK code, and waiting for response. Thought to mention the above sources to you in case you weren’t aware of and if your requirements could be fulfilled by what’s already available. Experts, please feel free to correct me if I am wrong somewhere.